Three people have come forward with hundreds of pages of evidence of potential wrongdoing by the Clinton Foundation, including misappropriation of funds and allegations of quid-pro-quo promises made to donors during Hillary Clinton’s tenure as secretary of state, Rep. Mark Meadows, R-N.C., told Fox News on Thursday.

Meadows, the leader of the conservative House Freedom Caucus, is also the chairman of the House Oversight Subcommittee on Government Operations. The panel is set to hold an investigative hearing next week on the status of the Foundation case.

U.S. Attorney John Huber was tasked to investigate the foundation last year by then-Attorney General Jeff Sessions.

The Clinton Foundation consistently has maintained that it is a charity, and never traded on Hillary Clinton’s position as America’s top diplomat, which she held from 2009-2013. The organization has a four-star rating from the watchdog site Charity Navigator and has touted its mission “to create economic opportunity, improve public health, and inspire civic engagement and service.”

However, The Hill reported Thursday that prosecutors working for Huber recently requested documents from a private investigative firm that also has been looking into the foundation. The firm, MDA Analytics LLC, reportedly has contacted the IRS, the Justice Department and the FBI’s Little Rock office with evidence from its own investigation.

In addition, The Hill reported that a whistleblower submission filed with the FBI and IRS in August 2017 included internal legal reviews that the Clinton Foundation conducted between 2008 and 2011. Those reviews raised concerns about legal compliance and improper mingling of personal and charity business.